1. Field of the Invention
The disclosed invention generally relates to an electromagnetic relay assembly incorporating a rotatable coil-core assembly. More particularly, the disclosed invention relates to an electromagnetic relay assembly having a magnetically actuable coil assembly rotatable about an axis of rotation extending orthogonally relative to the coil assembly axis.
2. Brief Description of the Prior Art
Generally, the function of an electromagnetic relay is to use a small amount of power in the electromagnet to move an armature that is able to switch a much larger amount of power. By way of example, the relay designer may want the electromagnet to energize using 5 volts and 50 milliamps (250 milliwatts), while the armature can support 120 volts at 2 amps (240 watts). Relays are quite common in home appliances where there is an electronic control turning on (or off) some application device such as a motor or a light. Several exemplary electromagnetic relay assemblies reflective of the state of the art and disclosed in United States patents are briefly described hereinafter.
U.S. Pat. No. 6,046,660 ('660 patent), which issued to Gruner, discloses a Latching Magnetic Relay assembly with a Linear Motor. The '660 patent describes a latching magnetic relay capable of transferring currents of greater than 100 amps for use in regulating the transfer of electricity or in other applications requiring the switching of currents of greater than 100 amps. A relay motor assembly has an elongated coil bobbin with an axially extending cavity therein. An excitation coil is wound around the bobbin. A generally U shaped ferromagnetic frame has a core section disposed in and extending through the axially extending cavity in the elongated coil bobbin.
Two contact sections extend generally perpendicularly to the core section and rises above the motor assembly. An actuator assembly is magnetically coupled to the relay motor assembly. The actuator assembly is comprised of an actuator frame operatively coupled to a first and a second generally U-shaped ferromagnetic pole pieces, and a permanent magnet. A contact bridge made of a sheet of conductive material copper is operatively coupled to the actuator assembly.
U.S. Pat. No. 6,246,306 ('306 patent), which issued to Gruner, discloses an Electromagnetic Relay with Pressure Spring. The '306 patent teaches an electromagnetic relay having a motor assembly with a bobbin secured to a housing. A core is adjacently connected below the bobbin except for a core end, which extends from the bobbin. An armature end magnetically engages the core end when the coil is energized. An actuator engages the armature and a plurality of center contact spring assemblies. The center contact spring assembly is comprised of a center contact spring which is not pre bent and is ultrasonically welded onto a center contact terminal.
A normally open spring is positioned relatively parallel to a center contact spring. The normally open spring is ultrasonically welded onto a normally open terminal to form a normally open outer contact spring assembly. A normally closed outer contact spring is vertically positioned with respect to the center contact spring so that the normally closed outer contact spring assembly is in contact with the center contact spring assembly, when the center contact spring is not being acted upon by the actuator. The normally closed spring is ultrasonically welded onto a normally closed terminal to form a normally closed assembly. A pressure spring pressures the center contact spring above the actuator when the actuator is not in use.
U.S. Pat. No. 6,252,478 ('478 patent), which issued to Gruner, discloses an Electromagnetic Relay. The '478 patent describes an electromagnetic relay having a motor assembly with a bobbin secured to a frame. A core is disposed within the bobbin except for a core end which extends from the bobbin. An armature end magnetically engages the core end when the coil is energized. An actuator engages the armature and a plurality of movable blade assemblies. The movable blade assembly is comprised of a movable blade ultrasonically welded onto a center contact terminal.
A normally open blade is positioned relatively parallel to a movable blade. The normally open blade is ultrasonically welded onto a normally open terminal to form a normally open contact assembly. A normally closed contact assembly comprised of a third contact rivet and a normally closed terminal. A normally closed contact assembly is vertically positioned with respect to the movable blade so that the normally closed contact assembly is in contact with the movable blade assembly when the movable blade is not being acted upon by the actuator.
U.S. Pat. No. 6,320,485 ('485 patent), which issued to Gruner, discloses an Electromagnetic Relay Assembly with a Linear Motor. The '485 patent describes an electromagnetic relay capable of transferring currents of greater than 100 amps for use in regulating the transfer of electricity or in other applications requiring the switching of currents of greater than 100 amps. A relay motor assembly has an elongated coil bobbin with an axially extending cavity therein. An excitation coil is wound around the bobbin. A generally U shaped ferromagnetic frame has a core section disposed in and extending through the axially extending cavity in the elongated coil bobbin.
Two contact sections extend generally perpendicularly to the core section and rises above the motor assembly. An actuator assembly is magnetically coupled to the relay motor assembly. The actuator assembly is comprised of an actuator frame operatively coupled to a first and a second generally U-shaped ferromagnetic pole pieces, and a permanent magnet. A contact bridge made of a sheet of conductive material copper is operatively coupled to the actuator assembly.
U.S. Pat. No. 6,563,409 ('409 patent), which issued to Gruner, discloses a Latching Magnetic Relay Assembly. The '409 patent describes a latching magnetic relay assembly comprising a relay motor with a first coil bobbin having a first excitation coil wound therearound and a second coil bobbin having a second excitation coil wound therearound, both said first excitation coil and said second excitation coil being identical, said first excitation coil being electrically insulated from said second excitation coil; an actuator assembly magnetically coupled to both said relay motor, said actuator assembly having a first end and a second end; and one or two groups of contact bridge assemblies, each of said group of contact bridge assemblies comprising a contact bridge and a spring.
Other patent disclosures of particular interest are U.S. Pat. No. 4,743,877, which issued to Oberndorfer et al.; U.S. Pat. No. 5,568,108, which issued to Kirsch; U.S. Pat. Nos. 5,910,759; 5,994,987; 6,020,801; 6,025,766, all of which issued to Passow; U.S. Pat. No. 5,933,065, which issued to Duchemin; U.S. Pat. No. 6,046,661, which issued to Reger et al.; U.S. Pat. No. 6,292,075, which issued to Connell et al.; U.S. Pat. No. 6,426,689, which issued to Nakagawa et al.; U.S. Pat. Nos. 6,661,319 and 6,788,176, which issued to Schmelz; U.S. Pat. No. 6,949,997, which issued to Bergh et al.; U.S. Pat. No. 6,940,375, which issued to Sanada et al.; and U.S. Patent Application Publication No. 2006/0279384, which was authored by Takayama et al.
The Schmelz, Duchemin, and certain of the Gruner disclosures were particularly relevant to the subject matter as described in U.S. Pat. No. 7,659,800 (the '800 patent) and U.S. Pat. No. 7,710,224 (the '224 patent), which issued to Gruner et al. The '800 and '224 patents describe electromagnetic relays essentially comprising a coil assembly, a rotor or bridge assembly, and a switch assembly. The coil assembly comprises a coil and a C-shaped core. The coil is wound round a coil axis extending through the core. The core comprises core termini parallel to the coil axis. The bridge assembly comprises a H-shaped bridge and an actuator.
The bridge comprises medial, lateral, and transverse field pathways. The actuator extends laterally from the lateral field pathway. The core termini are coplanar with the axis of rotation and received intermediate the medial and lateral field pathways. The actuator is cooperable with the switch assembly. The coil creates a magnetic field directable through the bridge assembly via the core termini for imparting bridge rotation about the axis of rotation. The bridge rotation displaces the actuator for opening and closing the switch assembly.
Notably, the Kirsch U.S. Pat. No. 5,568,108; the Reger et al. U.S. Pat. No. 6,046,661; the Nakagawa et al. U.S. Pat. No. 6,426,689; the Schmelz U.S. Pat. Nos. 6,661,319 and 6,788,176 and the Gruner et al. '800 and 224 patents teach or describe armature assemblies having an H-shaped portion pivotable about a pivot axis of rotation, which H-shaped portion comprises or is otherwise attached to an elongated actuator arm extending from the H-shaped portion.
It is noted that an inherent problem with conventional electromagnetic relays incorporating a coil assembly and an armature of the foregoing type(s) is that they are quite susceptible to magnetic tampering. This is primarily because the rotating armature houses a permanent magnet. These permanent magnets react to the magnetic field generated by the coil and are either repelled or attracted, thereby creating a mechanical motion to open and/or close the contacts.
This leaves the relay(s) vulnerable to tampering by using a very large magnet (i.e. positioning a large conflicting magnetic field) external to the relay. Since the permanent magnets are housed in a rotating plastic casing, this means t will only hold its state as long as no other magnetic or mechanical force is exerted to the relay which is larger than the magnetic holding force of the permanent magnets.
It is noted that certain international standards require that the relay hold its state in either the open or closed position when a magnetic field measuring at least 5000 Gauss is brought within 40 millimeters of the relay. During this test, many relays cannot operate due to the conflicting 5000 Gauss magnetic field. This type of tampering is common in developing countries or in lower income areas to turn the electricity meter back on after the utility company has remotely shut it off.
The prior art thus perceives a need for an electromagnetic relay that is resistant to magnetic tampering whereby the permanent magnets are fixed or anchored and the coil assembly itself rotates with minimized displacements so as to intensify the operative magnetic field otherwise inherent to the same size magnets.